AD,
Wiring reversing loops is not a big deal. There are several books available that have good diagrams and explanations that can help. Personally, I like "How to wire your model Railroad" by Linn Wescott, first published in 1950! But Andy Sperandeo's book on wiring is good also. You can buy either for a few bucks on Amazon or Ebay.
I assume you aren't going to install a DCC system because you wouldn't have to worry about reversing loops if you were.
If you a DC guy like me, don't let your LHS guy scare you away from reversing sections/loops. When I was a kid my LHS guy told me all I had to do to achieve multiple train operation was buy the dual power pack he had on sale!
I have wired loops, wyes, crossovers but haven't done a turntable yet. That is on my schedule for the layout I am currently building.
The key is determining where the reversing section(s) are based on your layout diagram and where you want to "turn" the train. (Reversing loop/sections need to be longer than longest train you intend to run.
I like dogbone layout designs because they give appearance of double track mainline. But remember if you install a crossover (I have 9 on my layout)between "mainlines" you have created a reversing section.
Not sure if this helps, but reversing loops/sections can add lots of interesting operating opportunities. Good luck!
Tim
Maybe now is the time to make the decision as to what type of control you are going to use. Dc control is inexpensive and easy to wire. DCC is a little more costly but by buying an entry level system that is expandable from Digitrax or NCE will simplify the wiring and especially reverse loops. Automatic reversing modules eliminate the confusion of wiring toggle switches. But you still have to isolate the reversing loop from the main. DCC automatic reversing modules instantly reverse the track power in the loop not the main so if you are running another train it will not reverse direction while it is on the main track.
Whether you use a DPDT switch or an electronic auto-reverser (AR), the wiring is the same.
Power to the DPDT or AR (input side) is accomplished by a pair of feeder wires from the main bus wires.
Power to the reversing section or loop is provided from the output side of the DPDT or AR by a pair(s) of feeder wires.
Any and all feeder wires to the reversing section or loop must come from the output side of the DPDT or AR. No feeder wires from the reversing section or loop should be connected to the main bus, and no feeder wires from the non-reversing section (or loop) should be connected to the output side of the DPDT or AR.
The other key to successful wiring of a reversing section or loop is isolation. The reversing section or loop must be completely isolated from the main (non-reversing) section of the layout. To completely isolate the reversing section or loop, gaps are place in the rails either by cutting the rails with a saw or Dremel or installing insulated (plastic) rail joiners. The exact number and placement of gaps depends upon the track configuration.
Rich
Alton Junction
If you go DC and want to run two trains on different sections simultaneously, perhaps consider the Atlas Controller and Selector devices. I believe they are still made (certainly available on EBay), are not expensive, and make wiring and operation easy. You just need the Controller for reversing the loop and the Selector(s) to manage which power supply is powering each other track section at a given time. These have been around 50-60 years so they are proven for sure.
http://www.atlasrr.com/pdf/Item220Instructions.pdf
http://www.modeltrainstuff.com/Atlas-220-Controller-p/atl-220.htm
Paul
Modeling HO with a transition era UP bent